For example, such optical components comprising an array of coupled waveguides are described in publication “Spatial photonics in nonlinear waveguide arrays”, Fleischer et al., Optics Express Vol. 13, No. 6, pp. 1780-1796 (2005). In this publication, the waveguides of the array are uniformly coupled in the array. The coupling uniformity within the array is obtained since two adjacent waveguides are coupled according to the same coupling coefficient within the array.
It is known that an optical signal may propagate in a guided fashion in such waveguide arrays. The optical signal propagating in such waveguide array is called “Floquet-Boch wave”, or “supermode” or “Schrodinger discrete modes” depending on the authors. In the frame of the following application, this signal will be referred to as guidonic wave. The guidonic wave is defined by its guidonic wave vector and the components of this vector have a relationship thereamong, called diffraction relationship. For instance, in the frame of a simple theory of in-plane coupled modes, if kx and kz are the two components of the guidonic wave vector along directions X and Z, in reduced units kz is proportional to 2 cos kx, the proportionality constant being equal to the coupling coefficient.
The optical signal processing in the array of coupled waveguides is particularly advantageous notably in the telecommunications field.
In such an array of coupled waveguides, in principle, the optical signal composed of a light beam propagates linearly, with a natural divergence which may be null.
Nevertheless, in particular, in the field of switch components for optical telecommunications, it would be advantageous that a light beam may be processed, and more particularly oriented, reflected or focused.
To this end, many solutions have been considered.
First, it is possible to output the light beam from the waveguide array, and to orient the beam by known mechanical means such as mirrors or diopters, or lenses.
Nevertheless, the drawback of this solution is that it has to be implemented outside the waveguide array, thus loosing the guiding of the light beam. Thus, the use of waveguide arrays is not very efficient in terms of integration. The invention particularly aims at remedying this drawback by providing a component allowing the processing of the signal within the array itself, so as to form an entirely optical component.
In order to statically deflect a beam in a waveguide array, it is known from publication “Approximate solution of Eigenmode Problems for coupled waveguide arrays”, Richard R. A. Syms, IEEE Journal of Quantum Electronics, vol. QE 25, n° 5, pp. 525-532 (1987), a waveguide array comprising an area of parallel highly coupled waveguides and an area of parallel weakly coupled waveguides so as to allow a static deflection at the interface between both areas. Nevertheless, in this publication, the simple deflection of the beam propagating in the waveguide array is too much restricted to be able to apply it in industrial components.
The original approach forming the basis of this invention is to use such waveguide arrays to obtain an optical component of a new type, making it possible to process the signal within the array itself, so as to form an entirely optical component.